Electrical switch having deformable contact members



April 13, 1965 B. A. GAY ETAL 3,178,540

ELECTRICAL SWITCH HAVING DEFORMABLE CONTACT MEMBERS Filed April 17, 19612 Sheets-Sheet 1 April 13, 1965 B. A. GAY ETAL 3,178,540

ELECTRICAL SWITCH HAVING DEFORMABLE CONTACT MEMBERS 2 Sheets-Sheet 2Filed April 1'7. 1961 INVENTQRS Ben amin A. Gay Donald A. Moyunt UnitedStates Patent 3,178,546 ELECTRECAL SWITCH HAVING DEFGRMAELE CONTACTMEMBERS Benjamin A. Gay and Donald A. Moyant, Tamaqna, Pa,

assignors to Atlas Chemical Industries, lino, Wilmington, Del acorporation of Delaware Filed Apr. 17, 1961, Ser. No. M3592 lll Claims.(Cl. 206-442) The present invention relates to an electrical switch, andin particular relates to an irreversible electrical switch particularlyadapted to be squib activated.

Certain types of vehicles which travel at high speeds require electricalswitches that are highly reliable and stable under conditions ofvibration, violent tumbling and sudden changes of direction. It istherefore an object of the present invention to provide a switch ofextremely rugged construction which will remain stable in a desiredconnect or disconnect position.

It is also an object of the present invention to provide a switch thatis highly reliable and capable of carrying high amperage and voltagewithout jump or breakdown.

It is a further object of the present invention to provide a switch ofvery small size and of low contact resistance.

It is a further object of the present invention to provide a switchwhich is easily adapted to be squib actuated.

A still further object of the present invention is to provide a switchwhich may easily be adapted to be high temperature safe, i.e., theswitch will be inoperative if exposed to high ambient temperatureconditions.

These and further objects will become apparent from the followingspecification and claims, particularly when considered in conjunctionwith the accompanying drawings.

The switch of the present invention comprises in combination a switchhousing, a movable piston member adpted to be received in the housing,and a contact assembly member having at least one pair of spacedelectrical contact members positioned therein. Each pair of electricalcontact members has a closed position wherein the members are in contactand an open position wherein the members are out of contact. Theelectrical contact members of each pair are so arranged in relation toeach other that a deformation of one member of the pair into a permanentset effects a change of the pair from one position to the other. Themovable piston member is positioned within the switch housing and ameans of driving the piston member is provided. Upon actuation of thepiston driving means, the piston member is moved toward the electricalcontact pairs to contact and deform into a permanent set a member ofeach pair and thereby effect a change of the pair from one position tothe other. A switch of the present invention is made temperaturesafe byfabricating the piston member of a material which so softens as to beincapable of actuating the contact members at an ambient temperaturebelow the temperature which is sufficient to thermally actuate thepiston driving means.

In a preferred arrangement, one electrical contact member of each pairhas movable or deformable portion and is bent in a direction toward thesecond or stationary member of the pair. The stationary memberpreferably has a broadened portion located along its length closest tothe movable member to facilitate a reliable physical contact between thepair. The movable or bent electrical contact member is preferablyfabricated of a malleable metal and is of sufficient length to reach andphysically contact the second or stationary member of the pair.

In case the electrical contact pair is to be connected, or closed, thecontact members of the pair are initially positioned out of physicalcontact and so arranged in relation to each other that a further bendingof the movable or deformable contact member toward the contact assemblymember, sumcient to cause physical contact between the contact pairmembers, causes the movable contact member to be deformed into apermanent set. In case the electrical contact pair is to bedisconnected, or opened, the contact members of the pair are initiallypositioned in physical contact and so arranged in relation to each otherthat a further bending of the movable contact member toward the contactassembly member, sufficient to cause the contact pair members to beseparated, causes the movable contact member to be deformed into apermanent set.

The term deformed into a permanent set is used herein to describe theamount that a movable or deformable electrical contact member is bent ordeformed, and should be interpreted as a bending or deforming to a pointthat the contact member will no longer regain its original form upon theremoval of the deforming force.

The electrical contact assembly member is adapted to be received in theswitch housing and in a preferred embodiment of the invention thecontact assembly member encloses one end of the switch housing. Theelectrical contact pair members are mounted in the contact assemblymember in such a manner that their connecting and disconnecting portionsare within the confines of the assembled switch. The movable pistonmember is adapted to be received and encased in the switch housing andis positioned between one end of the switch housing and the contactassembly member. The piston member is preferably recessed to receive thestationary contact members and is equipped with a non-conducting strikerportion to contact the ends of the movable or bent electrical contactmembers. In operation the piston member is caused to move toward theelectrical contacts mounted in the contact assembly member, thestationary contact members are received in the recessed portion of thepiston and the movable or deformable contact members are physicallycontacted by the striker portion of the piston and bent toward thecontact assembly member into a permanent set. The action of the pistoncauses the electrical contact members originally positioned in an openposition to move to a closed position and simultaneously causes theelectrical contact members originally positioned in a closed position tomove to an open position. In a preferred embodiment of the invention thepiston member is motivated by gas pressure directed on the face of thepiston member farthest from the contact assembly member. Preferably thegas pressure is obtained from an electrical squib means positionedwithin the switch housing.

Electrical connection of the switch in a circuit may easily beaccomplished by merely extending a portion of the electrical contactmembers through the contact assembly member to form external poleterminals.

The invention will be more clearly understood by reference to theaccompanying drawings in which similar reference numbers are used todenote similar elements throughout the several views.

FIGURE 1 is an exploded view of a switch in accord with this invention.

FIGURE 2 is a partial sectional view of the assembled switch shown inFIGURE 1.

FIGURES 3a and 3b are fragmentary perspectiveviews and show in detail apair of electrical contact members, similar to those of a switch asshown in FIGURES 1 and 2, mounted in a portion of contact assemblymember 33. FIGURE 3a shows a pair of contact members in a normally openposition. FIGURE 3b shows the pair of contact members of FIGURE 3a in aclosed position.

FIGURES 4a and 4b are fragmentary perspective views and show in detail apair of electrical contact members, similar to those of a switch asshown in FIGURES 1 and 2, mounted in a portion of contact assemblymember 33. FIGURE 4a shows a pair of contact members in a normallyclosed position. FIGURE 4b shows the pair of contact members of FIGURE4a in an open position.

Referring to FIGURE 1, numeral 11 refers to the switch housing generallycylindrical in shape and preferably fabricated of a metal. Suitablemetals, for example, are stainless steel or brass. Switch housing 11 hasan open end 13 and preferably has an extended lip portion 14. A pistonmember 15 is adapted to fit snugly within housing 11. Piston 15 isequipped with a center opening 17 therethrough, and has a recessedportion 19 and a non-conducting striker portion 21 along one face.Piston 15 is preferably fabricated entirely of a suitable non-conductingmaterial, nylon has been found to be eminently satisfactory. If piston15 is fabricated of a conductive material, a layer of insulatingmaterial such as nylon is placed on the surface of striker portion 21.If the piston member is fabricated of metal or a ceramic material, anO-ring 23 may be positioned around the circumference of the pistonmember to insure a gastight fit between the piston and the switchhousing. electrical squib member 25 having leg wires 27 and 27 isadapted to be snugly received by center opening 17 of piston 15. Squib25 is equipped with a neck portion 29 adapted to be received by anannular collar 31 extending from electrical contact assembly member 33.Annular collar 31, is in turn, adapted to be snugly received in centeropening 17 of piston 15. Electrical contact assembly member 33 has aplurality of electrical contacts such as 37, 37, 5'7 and 57 positionedtherethrough. The ends of contact members extend through face 35 ofcontact assembly member 33 and form pole terminals such as 55 and 55'.Preferably the contact assembly member 3-3 is fabricated of metal and insuch case the electrical contacts such as 37, 37', 57 and 57' aredesirably insulated from electrical contact with the contact assemblymember by means of glass or plastic insulating beads 38 placed aroundthe electrical contacts at the points at which they pass through thecontact assembly member. Contact assembly member 33 is preferablyequipped with a center opening 20 adapted to receive the lead wires 27and 27' of squib 25. An annular flange portion 41 of the contactassembly member is adapted to be received in the open end 13 of switchhousing 11 and annular surface 43 is adapted to seat on annular lip 14of switch housing 11.

FIGURE 2 shows a partial sectional view of the switch of FIGURE 1 as itwould appear if it were assembled. Switch housing 11 contains a snuglyfitting piston member 15 having a central opening therethrough toreceive a portion of squib 25. Squib 25, not shown in section, is anitem of commerce readily available from explosives suppliers. Piston 15is shown as equipped with an O-ring 23 to insure a snug fit with theinternal surface of housing 11. FIGURE 2 shows an additional O-ring 24,not seen in FIGURE 1, which may be utilized to insure a snug fit betweenpiston member 15 and annular collar 31.

Piston 15 has an annular recessed portion 19 to receive the stationarycontact members, such as 37 and 57. Surface 21 of piston 15 ispositioned in relation to the ends of the bent contact members such as37 and 57' in such a manner that movement of the piston toward theelectrical contact members results in physical contact between strikerportion 21 of the piston member, and the ends of the movable contactmembers. Further movement of the piston toward the movable contactmembers then causes a bending of the movable contact members towardcontact assembly 33. A detailed description of the electrical connectionand disconnection of the pairs of electrical contact members follows inthe discussion of FIGURES 3a, 3b, and 4a and 4b. Annular collar 31 isadapted to seat on shoulder 46 of squib 25 and contact assembly member33 is adapted 4. to be tightly secured to the switch housing 11 alongsurface 43 and flange portion 41.

It is to be noted from FIGURE 2 that the expanding gases from a firingof squib 25 would be directed to area 49 underlying squib 25 and towardsurface 26 underlying piston 15. In a preferred embodiment of theinvention piston member 15 is fabricated of a plastic material and thesudden pressure directed on surface 26 will cause distortion of thepiston and result in a substantially gastight seal along the surfacesbetween the piston member and the switch housing and between the pistonmember and the contact assembly member. Piston member 15 is securedagainst movement along the vertical axis of the switch against externalforces such as shock and vibration by a securing flange 49. Upon therelease of gases from a squib source into area 49, securing flange 4&3is ruptured or deformed and piston member 15 is then allowed freemovement along the vertical axis of the switch toward contact assemblymember 33 and is rapidly and forcefully moved in that direction byexpanding squib gases. Striker portion 21 of piston member 15 is forcedagainst the movable contact members such as 37' and 57 causing them tobe permanently deformed in the direction of contact assembly member 33.

FIGURES 3a and 3b are fragmentary perspective views showing in detail apair of electrical contact members such as 37 and 37 and a portion ofcontact assembly member 33. The contact members are depicted in an openposition in 3a and in a closed position in 3b. The electrical contactmembers are insulated from contact assembly member 33 by anon-conducting bead or sleeve 38. A bending of end portion 47 of movablecontact member 37 in a direction toward contact assembly member 33 untilphysical contact between contact member 37 and broadened portion 49 ofstationary contact member 37 is obtained causes contact member 37 to beformed into a permanent set.

FIGURES 4a and 4b are fragmentary perspective views showing in detail apair of electrical contacts such as 57 and 57' and a portion of contactassembly member 33. The contact members are depicted in a closedposition in 4a and in an opened position in 4b. The electrical contactmembers are insulated from contact assembly member 33 by anon-conducting bead or sleeve 38. A bending of end portion 51 of movablecontact member 57 in a direction toward contact assembly member 33 untilphysical contact between contact member 57 and broadened portion 53 ofstationary contact member 57 is broken causes contact member 57 to bedeformed into a permanent set.

The electrical contact members, such as 37, 37 57 and 57, are preferablyfabricated of a malleable metal having little or no Spring-back ability.Contact members of malleable brass or nickel-iron alloy have been foundto be eminently satisfactory. It is to be noted that the positive andstable positions of the electrical contact members in the switch of thepresent invention eliminates chatter, i.e., undesired making andbreaking of electrical contact when the switch is exposed to rigorousagitation or violent vibration.

The switch of the present invention is designed to be easily adapted toa temperature-safe switch wherein the device will not perform aswitching function if the switch is exposed to a high temperature suchas might be encountered in flareups during vehicle launching or in caseof a conflagration in a vehicle storage area. In an embodiment of atemperature-safe switch of the present invention, the piston member isfabricated of a thermoplastic material which so softens at a temperaturelower than the thermal ignition temperature of the squib that isincapable of moving the electrical contact members to activate theswitch. Nylon or a plastic material marketed by the General ElectricCompany under the trademark of Lexan-IOO melt at about 400 F. and havebeen found to be eminently satisfactory for fabrication of the pistonmember when used in conjunction with a squib containing an ignition dropcomprised of a mixture of lead mononitroresorcinol and potassiumchlorate in a weight ratio of about 90/10 held together by a smallamount of inert binder material, and a base charge comprised of amixture of lead mononitroresorcinol and potassium chlorate in a Weightratio of about 95/5. Such a squib has a thermal ignition temperature ofabout 500 F. If the squib is ignited after the piston has melted theexpanding gases from the squib source will force their way through andaround the softened or melted piston member to fill the internal volumeof the switch. Under such circumstances, no directed force will beapplied to the movable contact members and the pairs of contact memberswill remain stable in their original present positions.

What is claimed is:

1. An electrical switch comprising a switch housing containing a movablepiston member and a plurality of pairs of electrical contact members,each pair of electrical contact members having a closed position whereinthey are in contact and an open position wherein they are out ofcontact, said electrical contact members of each pair positioned inrelation to each other so that deformation of one member of the saidcontact pair into a permanent set effects a change of said pair from oneof said positions to the other of said positions, means within saidswitch housing to drive said movable piston toward said contact members,said contact members positioned so that upon movement of said pistonmember said piston member contacts and deforms into a permanent set onemember of each contact pair and thereby causes the pairs of contactmembers to change from one of said positions to the other of saidpositions.

2. An electrical switch comprising a switch housing having side wallsand first and second end walls, one end wall comprising a contactassembly member, said contact assembly member having at least one pairof electrical contact members extending therethrough and insulatedtherefrom, said electrical contact members having a closed position inwhich they are in contact and an open position in which they are out ofcontact, said electrical contact members of each pair positioned inrelation to each other so that deformation of one member of the saidcontact pair into a permanent set effects a change of said pair from oneof said positions to the other of said positions, a nonconductingmovable piston member positioned within said switch housing, means fordriving said movable piston toward said contact assembly member tocontact and deform into a permanent set one member of each pair of saidelectrical contact members and thereby cause said pairs of electricalcontact members to change from one of said positions to the other ofsaid positions.

3. The electrical switch of claim 2 wherein the movable piston member isconstructed of a rigid, non-conducting plastic.

4. An electrical switch comprising a switch housing having side wallsand first and second end walls, said housing containing a movable pistonmember, one end wall comprising a contact assembly member, said contactassembly member having a plurality of pairs of deformable electricalcontact members extending therethrough, each of said pairs of electricalcontact members capable of being positioned in one of two positions, aclosed position wherein the members of each pair are in contact witheach other and an open position wherein the members of each pair are outof contact, said positions located in relation to each other that achange from one to the other requires sufiicient bending of contacts asto cause them to be permanently set, said movable piston memberpositioned within the switch housing between said end walls, means fordriving said piston member toward said contact assembly member, saidpiston member having a non-conducting striker portion adapted to contactand deform into a permanent set a contact member of each pair andthereby cause the electrical contact members originally posi- '5 tionedin an open position to move to a closed position and simultaneously theelectrical contact members originally positioned in a closed position tomove to an open position.

5. An electrical switch comprising a switch housing containing a movablepiston member, said piston member having a non-conducting strikerportion, and a plurality of pairs of electrical contact members, onemember of each pair being of a malleable metal and in a position to bebent into a permanent set by the striker portion of said piston member,the other member of each pair being in a position not to be bent by thestriker portion of said piston member, each pair of electrical contactmembers having a position in which the members are in contact and aposition in which the members are out of contact, said electricalcontact members of each pair are positioned in relation to each other sothat deformation of one member of the said contact pair into a permanentset effects a change of said pair from one of said positions to theother of said positions, means for driving said movable piston membertoward said contact pairs to contact and bend said malleable metalcontact member of each of said pairs into a permanent set and therebycause each pair of electrical contact members to change from one of saidpositions to the other.

6. A switch comprising a plurality of pairs of electrical contactmembers and a movable piston member, each of said pairs of electricalcontact members comprising a stationary and a deformable member, saiddeformable contact member of each pair comprised of a malleable metal,each of said pairs of contact members having a position wherein the pairmembers are in contact and a position wherein the pair members are outof contact, said electrical contact members of each pair are positionedin relation to each other so that deformation of one member of the saidcontact pair into a permanent set effects a change of said pair from oneof said positions to the other of said positions, said movable pistonmember having a non-conducting striker portion adapted to contact andbend said deformable member into a permanent set and thereby cause saidpairs of contact members to permanently change from one of saidpositions to the other of said positions.

7. An electrical switch comprising a switch housing having side walls,first and second end walls, one end Wall comprising a contact assemblymember, said housing containing a piston member, said contact assemblymember having at least one pair of electrical contact members therein,and extending toward said piston member, each pair of electrical contactmembers comprising one stationary contact member and one deformablecontact member adapted to be bent into a permanent set position, saidcontact members having tWo positions, a closed position in which themembers of each contact pair are in contact with each other and an openposition in which each member of the contact pair is out of contact withthe other, one of said members of each pair being bent into a permanentset when said contact members change from one position to the other,said piston member having a first position wherein said piston member isbetween the base portion of said switch housing and said contactassembly and is out of contact with said contact members, and beingmovable to a second position wherein the piston is in contact with saidelectrical contact members, deformable securing means holding saidpiston member in said first position, said piston member having anon-conducting striker portion adapted to contact and deform into a permanent set said deformable electrical contact members and thereby causesaid contact members to move from one position to the other if saidpiston member moves from its first position to its second position, andmeans for deforming said deformable securing means and driving said piston member from one position to the other.

8. The switch of claim 6 wherein the means for driving said pistonmember is an explosive squib.

9. An explosively operated switch comprising an explosive squib, apiston member adapted to be moved by gas pressure from the firing ofsaid squib, and a switch means actuated by movement of said piston, saidpiston member being constructed of a material which so softens as to beincapable of actuating said switch means, at an ambient temperaturebelow that sufficient to thermally ignite said squib.

10. An explosively operated switch adapted to be nonoperative at hightemperatures containing a normally rigid piston member, a squib memberand electrical contact members having an open and a closed position,said piston member positioned intermediate the discharge end of saidsquib and the electrical contact members, said piston member adapted tobe moved by gas pressure from the firing of said squib means, saidelectrical contact members adapted to be moved from one of saidpositions to the other by movement of said piston member, said pistonmember adapted to soften and become incapable of moving said electricalcontact members at a temperature level of about 400 F., and said squibmember adapted to thermaily ignite at a temperature above the saidsoftening point of said piston member.

11. The switch of claim 10 wherein the piston member is fabricated ofnylon.

References Cited by the Examiner UNITED STATES PATENTS BERNARD A.GILHEANY, Primary Examiner.

WALTER STOLWEIN, Examiner.

1. AN ELECTRICAL SWITCH COMPRISING A SWITCH HOUSING CONTAINING A MOVABLEPISTON MEMBER AND A PLURALITY OF PAIRS OF ELECTRICAL CONTACTS MEMBERS,EACH PAIRS OF ELECTRICAL CONTACT MEMBERS HAVING A CLOSED POSITIONWHEREIN THEY ARE IN CONTACT AND AN OPEN POSITION WHEREIN THEY ARE OUT OFCONTACT, SAID ELECTRICAL CONTACT MEMBERS OF EACH PAIR POSITIONED INRELATION TO EACH OTHER SO THAT DEFORMATION OF ONE MEMBER OF THE SAIDCONTACT PAIR INTO A PERMANENT SET EFFECTS A CHANGE OF SAID PAIR FROM ONEOF SAID POSITIONS TO THE OTHER OF SAID POSITIONS, MEANS WITHIN SAIDSWITCH HOUSING TO DRIVE SAID MOVABLE PISTON TOWARD SAID CONTACT MEMBERS,SAID PISTON MEMBERS POSITIONED SO THAT UPON MOVEMENT OF SAID PISTONMEMBERS SAID PISTON MEMBER CONTACTS AND DEFORMS INTO A PERMANENT SET ONEMEMBER OF EACH CONTACT PAIR AND THEREBY CAUSES THE PAIR OF CONTACTMEMBERS TO CHANGE FROM ONE OF SAID POSITIONS TO THE OTHER OF SAIDPOSITIONS.